This experiment was performed to evaluate the effect of drinking Thyme essence on performance, immune condition and some blood parameters in broiler chickens. A total number of 500 Ross-308 male broiler chickens were allocated randomly to 4 treatments and 5 replicates using a CRD statistical design. Treatments were included plane water as control group and levels of 1, 1.5 and 2 ml of thyme essence in drinking water as experimental groups. Experimental traits were performance indices, serum antibody levels of important viral diseases, and some blood parameters at 21 and 42 days of age. Results showed that different levels of thyme essence had a significant effect on performance and blood parameters (P<0.05). Feed intake, daily gain, feed conversion and efficiency of energy and protein consumption significantly improved through thyme essence treatments compared to control group (P<0.05). Serum antibody levelsof viral diseases did not significantly affected by different levels of thyme essence (P>0.05). Concentration of HGB, percentage of HCT and number of RBC and WBC at 21 and 42 days of age were significantly higher in thyme essence treatments compared to control (p<0.05). As a final result, use of thyme essence in drinking water of broilers recommended at levels of 1.5 and 2 ml per each liter due to its positive effects on performance health and blood parameters of birds

Cross, D.E., R.M. McDevitt., K. Hilman., and T. Acamovic (2007) The effect of herbs and their associated essential oils on performance, dietary digestibility and gut microflora in young chicks from 7-28 days of age British Poultry Science, Original Vol 48(4): 496-506.